Socket-less pipe joints

Abstract

To provide an electrically conductive path between metal pipes, e.g. soil or drain pipes, connected at butting ends by means of an annular gasket of electrically insulating material which fits around and spans the butting ends and is secured in sealing engagement with the butting ends by clamp, a bridge element of electrically conductive material retained to the gasket extends between and engages with the pipes. The bridge element is conveniently an attachment to the gasket having portions disposed at internal and external circumferential surfaces of the gasket. Teeth or like formations on the bridge element dig into the surfaces of the pipes to enhance the engagement. Electrically conductive engagement may also be made with the clamp at a portion of the bridge element at the exterior of the gasket.

What is claimed is: 
     
       1. A socket-less pipe joint between butting ends of two metal pipes comprising: a tubular gasket of flexible electrically insulating material having internal and external circumferential surfaces and which is fitted over and spans said butting ends, there being an internal intermediate annular rib projecting from said internal circumferential surface which fits between and is abutted by said butting ends and further internal annular ribs which project from said internal circumferential surfaces, are spaced from said intermediate annular rib towards the opposite ends of said gasket and sealingly engage circumferentially around said butting ends;   a bridge element of electrically conductive material being of substantially rigid strip form of a width substantially less than the circumference of said gasket and attached to said gasket longitudinally thereof, and having an intermediate portion which is disposed at said external circumferential surface and end portions which extend through the material of said gasket, lie against said internal circumferential surface at opposite sides of said intermediate annular rib, between that rib and said further internal annular ribs, in engagement with said butting ends; and   clamping means substantially co-extensive with said gasket extending circumferentially about said gasket, bearing on said intermediate portion of said bridge element and compressively sealing said gasket around said butting ends and urging said end portions of said bridge element into engagement with said butting ends, the construction and arrangement being such that said bridge element provides an electrically conductive path between said pipes without interfering with the fit of said intermediate annular rib between said butting ends and the integrity of the circumferential sealing engagement of said further internal annular ribs with said butting ends.   
     
     
       2. A socket-less pipe joint according to claim 1 wherein said clamping means includes a part of electrically conductive material which bears on said intermediate portion of said bridge element such that an electrically conductive path is provided between said pipes and said clamping means. 
     
     
       3. A socket-less pipe joint according to claim 1 wherein said end portions of said bridge element have sharp-edged formations which protrude therefrom away from said intermediate portion and dig into surfaces of said butting ends. 
     
     
       4. A socket-less pipe joint according to claim 3 wherein said sharp-edged formations comprise corners of said end portions bent to form teeth which protrude from said end portions away from said intermediate portion. 
     
     
       5. A socket-less pipe joint according to claim 3 wherein said sharp-edged formations comprise teeth formed at edges of said end portions, there being slits in said edges and the material of said strip adjacent to said slits being bent to form said teeth. 
     
     
       6. A socket-less pipe joint according to claim 3 wherein said sharp-edged formations are protruding jagged edges of holes pierced out of said strip. 
     
     
       7. A socket-less pipe joint according to claim 1 wherein said bridge element has corrugations extending laterally thereof at said intermediate portion and said end portions. 
     
     
       8. A bridge element constructed and arranged to be attached to a tubular gasket of flexible electrically insulating material which has internal and external circumferential surfaces, fits over and spans butting ends of two metal pipes, has an internal intermediate annular rib projecting from the internal circumferential surface which fits between and is abutted by the butting ends and further internal annular ribs which are spaced from the intermediate rib towards opposite ends of the gasket and project from the intended circumferential surface to sealingly engage circumferentially around the butting ends, and which gasket is compressed into sealing engagement with the butting ends by clamping means substantially coextensive with the gasket applied circumferentially about the gasket to secure the butting ends of the pipes together in sealed relationship; said bridge element being of electrically conductive material in the form of a substantially rigid strip of a width substantially less than the circumference of the gasket having an intermediate portion and opposite end portions and having at said end portions sharp-edged formations which protrude from a surface thereof, and said bridge element being adapted to be attached longitudinally of the gasket with said intermediate portion lying on the external circumferential surface of the gasket where it is engageable by the clamping means, and with said end portions bent to extend through the material of the socket and then lie against the internal circumferential surface of the gasket substantially parallel to said intermediate portion at opposite sides of the intermediate annular rib of the socket, between that rib and the further internal ribs, in contact with the butting ends of the pipes and with said sharp-edged functions protruding away from said intermediate portion so as to be able to dig into the surfaces of the pipes, thereby to provide an electrically conductive path between the pipes without interfering with the fit of the intermediate rib of the gasket between the butting ends and the integrity of the circumferential sealing engagement of the further internal annular ribs with the butting ends.   
     
     
       9. A bridge element according to claim 8 wherein said sharp-edged formations comprise corners of said end portions which are bent to form teeth which protrude from said end portions. 
     
     
       10. A bridge element according to claim 8 wherein said sharp-edged formations comprise teeth formed at edges of said end portions, there being slits in said edges and the material of said strip adjacent to said slits being bent to form said teeth. 
     
     
       11. A bridge element according to claim 8 wherein said sharp-edged formations are protruding jagged edges of holes pierced out from said strip at said end portions. 
     
     
       12. A bridge element according to claim 8 wherein said strip is formed with corrugations which extend laterally of said strip. 
     
     
       13. A bridge element according to claim 8 wherein said intermediate portion has sharp-edged formations which protrude therefrom and are intended to dig into a surface of the clamping means.